In his State of the Union address to the American people earlier this year, Barack Obama declared that he was "confident" of achieving "our objective of defeating the core of al-Qaeda". Although he acknowledged the need to pursue the "remnants" of the terrorist group and its affiliates, the overall message was clear – al-Qaeda was badly degraded, the tides of war were receding and the US was winning this fight that was no longer even officially a war. The Boston bombings would appear to present a fundamental challenge to that assessment and once again bring the nagging uncertainty of terrorism...